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WO2025195682A1 - Procédé de fonctionnement d'un processus de synthèse d'ammoniac au niveau d'une charge partielle, et processus de synthèse d'ammoniac à charge partielle - Google Patents

Procédé de fonctionnement d'un processus de synthèse d'ammoniac au niveau d'une charge partielle, et processus de synthèse d'ammoniac à charge partielle

Info

Publication number
WO2025195682A1
WO2025195682A1 PCT/EP2025/053737 EP2025053737W WO2025195682A1 WO 2025195682 A1 WO2025195682 A1 WO 2025195682A1 EP 2025053737 W EP2025053737 W EP 2025053737W WO 2025195682 A1 WO2025195682 A1 WO 2025195682A1
Authority
WO
WIPO (PCT)
Prior art keywords
ammonia
gas
synthesis
reactor
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/053737
Other languages
German (de)
English (en)
Inventor
Michael Reinke
Robert Kender
Steffen Fahr
Harald Klein
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Linde GmbH
Original Assignee
Linde GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Linde GmbH filed Critical Linde GmbH
Publication of WO2025195682A1 publication Critical patent/WO2025195682A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01CAMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00Ammonia; Compounds thereof
    • C01C1/02Preparation, purification or separation of ammonia
    • C01C1/04Preparation of ammonia by synthesis in the gas phase
    • C01C1/0405Preparation of ammonia by synthesis in the gas phase from N2 and H2 in presence of a catalyst
    • C01C1/0482Process control; Start-up or cooling-down procedures
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00Operating or servicing cells
    • C25B15/08Supplying or removing reactants or electrolytes; Regeneration of electrolytes
    • C25B15/081Supplying products to non-electrochemical reactors that are combined with the electrochemical cell, e.g. Sabatier reactor
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00Electrolytic production of inorganic compounds or non-metals
    • C25B1/01Products
    • C25B1/02Hydrogen or oxygen
    • C25B1/04Hydrogen or oxygen by electrolysis of water

Definitions

  • the invention relates to a process for the synthesis of ammonia, in which a gas mixture comprising hydrogen and nitrogen (make-up gas) is provided with a time-varying flow rate to form an ammonia synthesis gas, which, after a compression step, is converted in an ammonia reactor to an ammonia-containing synthesis product, from which a recycle gas comprising hydrogen and nitrogen is separated in order to be returned via a return line to form the ammonia synthesis gas, wherein the flow rate of the recycle gas is controlled via an adjustable throttle device arranged in the return line and integrated as an actuator in a control loop.
  • the invention relates to a device for carrying out the method according to the invention.
  • Ammonia is one of the world's most widely produced chemicals. It serves primarily as a raw material for the production of fertilizers, but is also gaining increasing importance as an energy source and hydrogen storage medium. On an industrial scale, it is synthesized almost exclusively from nitrogen and hydrogen using the Haber-Bosch process. The synthesis reaction involved
  • N 2 + 3H 2 ⁇ -> 2NH 3 is exothermic and volume-decreasing, so that the reaction equilibrium shifts towards the ammonia side with decreasing temperature and increasing pressure.
  • the present invention has for its object to provide a method and a device of the generic type by which a shutdown of the ammonia reactor can be avoided, the fatigue of the synthesis circuit due to pressure cycling can be reduced and the speed of the load changes can be increased compared to the prior art.
  • control circuit is designed with a higher-level control which outputs a control signal dependent on the load of the ammonia reactor for changing the degree of opening of the throttle device, which is corrected by a PID control circuit in such a way that the pressure in the ammonia reactor always lies within a predetermined value range.
  • the flow resistance of the recycle line is increased by reducing the flow cross-section of the throttle device. This reduces the flow through the ammonia reactor more than would be the case due to the reduced amount of make-up gas alone. Since the reaction rate, which indicates the proportion of the reactant stream used that is converted to ammonia in a single pass through the ammonia reactor, is limited by the pressure-dependent reaction equilibrium, it cannot increase sufficiently to compensate for the reduced reactant feed to the reactor. Consequently, the reaction rate is reduced by increasing the flow resistance in the synthesis circuit, so that when the plant load is reduced, the pressure in the synthesis cycle decreases less than without the use of the throttle device, or remains constant or even increases.
  • the process according to the invention makes it possible to avoid a pressure drop in the ammonia reactor and other parts of the synthesis cycle by up to 95%, or at least significantly reduce it compared to the state of the art, while reducing the plant load. Fluctuations in the amount of available make-up gas therefore result in little or no mechanical stress on the device used for ammonia synthesis.
  • the ammonia reactor in particular, is subjected to less stress and can therefore be designed more cost-effectively. Shutting down the ammonia reactor is only necessary when the plant load drops below 5% of full load.
  • the exothermic synthesis reaction can, according to the state of the art, be extinguished in partial load operation, which is inhibited to such an extent by an excessive pressure drop that the reaction heat released is no longer sufficient to supply the reactant stream with the required activation energy before it enters the first catalyst bed.
  • the process according to the invention counteracts this adverse effect, since the released reaction heat leads to a greater temperature increase in the ammonia reactor at the higher pressure than in the prior art, and the reduced flow rate in the synthesis circuit results in more effective heat recovery in all intercoolers of the ammonia reactor and in other heat exchangers. Furthermore, due to the longer residence time of the reactant stream in the catalyst beds of the ammonia reactor, the synthesis reaction proceeds almost to equilibrium even at comparatively low inlet temperatures.
  • the flow cross-section of the throttle device can be adjusted by the operating personnel, who ensure that the pressure in the ammonia reactor remains within the specified range. This solution is particularly useful when the make-up gas flow rate changes only rarely and slowly.
  • the adjustable throttle device is equipped with an actuator and integrated as an actuator into a control loop, with which the reactor pressure is automatically maintained within the specified value range without human intervention.
  • the higher-level control system used according to the invention e.g., feed-forward control, model-predictive control
  • the PID control loop interacts with the PID control loop to reduce pressure fluctuations in the synthesis circuit and maintain the reactor pressure at a specified setpoint without any permanent control deviation.
  • the PID control loop is used to correct the flow cross-section of the throttle valve specified by the higher-level control system in order to maintain the reactor pressure at a specified setpoint without any permanent control deviation at all load conditions between 5 and 100%. This compensates for modeling uncertainties and the influence of undetectable or detectable disturbances.
  • the correction range of the PID controller is a subrange of the maximum possible cross-section change of the throttle valve.
  • the adjustable throttle device is open to a predetermined degree of opening or flow cross-section. Starting from this full-load cross-section, the flow cross-section can be reduced as soon as the pressure in the ammonia reactor is lower than the pressure at full load. However, it is also possible to reduce the flow cross-section of the adjustable throttle device only when the pressure falls below a predetermined threshold value below the full-load pressure. If necessary, the flow cross-section can be increased beyond the design point by further opening the adjustable throttle device.
  • the process according to the invention is expediently carried out in such a way that the pressure in the ammonia reactor does not fall below a limit value determined by corresponding regulations, such as in particular the ASME VIII/2 code or DIN EN 13445-3, so that a design of the components of the synthesis circuit for pressure cycling, which is associated with increased investment costs, is avoided.
  • the invention relates to a device for the synthesis of ammonia, comprising an ammonia reactor which is connected to a mixing device, a compressor, a separator and a return line to a synthesis circuit, wherein a gas mixture comprising hydrogen and nitrogen (make-up gas) can be supplied to the mixing device via a supply device with a time-fluctuating flow rate in order to form an ammonia synthesis gas which can be passed on via the compressor to the ammonia reactor for conversion into an ammonia-containing synthesis product, from which a recycle gas comprising hydrogen and nitrogen can be separated in the separator in order to be supplied to the mixing device via the return line, wherein the return line has an adjustable throttle device which is integrated into a control circuit as an actuator and via which the flow rate of the recycle gas can be controlled.
  • the mixing device can be designed as a pipe section, each with an inlet for the make-up and recycle gases, and an outlet for the ammonia synthesis gas.
  • the mixing device can also be part of a compressor used to drive the synthesis cycle, which has at least one low-pressure section and one high-pressure section arranged in series with the latter, with the mixing device being arranged between the low-pressure and high-pressure sections.
  • the pressure of the make-up gas 1 consisting of hydrogen and nitrogen, supplied from a source not shown with a temporally fluctuating flow rate, is increased in the compressor V1 before it is combined with the hydrogen- and nitrogen-rich recycle gas 2 in the mixing device M to form the ammonia synthesis gas 3.
  • the compressor V2 which can be mechanically coupled to the compressor V1
  • the ammonia synthesis gas 4 is preheated in the heat exchanger E3 against the synthesis product 5 to be cooled, so that it is ready at a temperature between 100 and 250°C, preferably between 140 and 210°C as preheated ammonia synthesis gas 6 for introduction into the ammonia reactor R.
  • the ammonia synthesis gas 6 is heated further if necessary and then at a pressure between 80 and 300 bar with catalytic support to form the ammonia-containing synthesis product 5 comprising unreacted hydrogen and nitrogen, which leaves the ammonia reactor R at a temperature between 400 and 470°C.
  • the synthesis product 5 is cooled to below the ammonia dew point, whereby a large part of the ammonia contained condenses out and a two-phase mixture of substances 7 is formed, which is separated in the separator D into a liquid fraction 8 consisting largely of ammonia and a gas fraction 9 containing uncondensed ammonia and unreacted hydrogen and nitrogen.
  • the liquid fraction 8 is withdrawn via the throttle device a as ammonia product
  • the gas fraction 9 is warmed in the heat exchanger E5 against the synthesis product 5 to be cooled and returned to the mixing device M as recycle gas 2 via the throttle device b.
  • the PC control system Based on the specified flow cross-section, the PC control system also specifies a range within which the cross-section can be corrected. For this correction, the reactor pressure measured by the pressure sensor P is compared with a stored setpoint, resulting in a corrected control signal within the specified range, which the PC control system transmits to the throttle device b, which is equipped with an actuator.
  • reaction rate which indicates the proportion of the ammonia synthesis gas 4 used that is converted to ammonia in a single pass through the ammonia reactor, is limited by the pressure-dependent reaction equilibrium, they do not increase sufficiently to compensate for the reduced amount of

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Automation & Control Theory (AREA)
  • Analytical Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention se rapporte à un procédé et à un dispositif de synthèse d'ammoniac (8), dans lequel un mélange gazeux (1) comprenant de l'hydrogène et de l'azote présente un débit massique fluctuant dans le temps pour former un gaz de synthèse d'ammoniac (3), qui est converti en un produit de synthèse contenant de l'ammoniac (5) dans un réacteur à ammoniac (R) après une étape de compression (V2) et à partir duquel un gaz recyclé (2) comprenant de l'hydrogène et de l'azote est séparé pour être renvoyé par une conduite de retour pour former le gaz de synthèse d'ammoniac (3), le débit massique du gaz recyclé (2) étant régulé au moyen d'un dispositif d'étranglement réglable (b) qui est disposé dans la conduite de retour (2) et qui est intégré dans un circuit de commande en tant qu'actionneur. L'invention est caractérisée en ce que le circuit de commande est conçu avec un système de commande en boucle fermée de niveau supérieur qui émet un signal d'actionnement, qui est basé sur la charge du réacteur à ammoniac, pour modifier le degré d'ouverture du dispositif d'étranglement (b), ledit signal d'actionnement étant corrigé par un circuit de commande de PID de telle sorte que la pression dans le réacteur à ammoniac (R) soit toujours dans une plage de valeurs spécifiée.
PCT/EP2025/053737 2024-03-20 2025-02-12 Procédé de fonctionnement d'un processus de synthèse d'ammoniac au niveau d'une charge partielle, et processus de synthèse d'ammoniac à charge partielle Pending WO2025195682A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP24020087.3 2024-03-20
EP24020087.3A EP4620913A1 (fr) 2024-03-20 2024-03-20 Procédé de fonctionnement d'une synthèse d'ammoniac en charge partielle et synthèse d'ammoniac en charge partielle

Publications (1)

Publication Number Publication Date
WO2025195682A1 true WO2025195682A1 (fr) 2025-09-25

Family

ID=90417587

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2025/053737 Pending WO2025195682A1 (fr) 2024-03-20 2025-02-12 Procédé de fonctionnement d'un processus de synthèse d'ammoniac au niveau d'une charge partielle, et processus de synthèse d'ammoniac à charge partielle

Country Status (2)

Country Link
EP (1) EP4620913A1 (fr)
WO (1) WO2025195682A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012037571A2 (fr) 2010-09-17 2012-03-22 Robertson John S Systèmes de stockage et de conversion d'énergie
WO2021089276A1 (fr) * 2019-11-08 2021-05-14 Casale Sa Contrôle d'une boucle de synthèse d'ammoniac à charge partielle
AU2021276065A1 (en) * 2020-05-18 2023-02-02 Topsoe A/S Method for the control of pressure in a loop for the preparation of ammonia or methanol
WO2023099743A1 (fr) * 2021-12-03 2023-06-08 Thyssenkrupp Industrial Solutions Ag Procédé permettant de faire fonctionner un système à ammoniac et installation de fabrication d'ammoniac
WO2023217850A1 (fr) * 2022-05-12 2023-11-16 Casale Sa Méthode de contrôle d'un convertisseur d'ammoniac ou de méthanol
EP4332694A1 (fr) * 2022-08-12 2024-03-06 Air Products and Chemicals, Inc. Procédé et système de commande de production et de stockage de gaz industriels

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012037571A2 (fr) 2010-09-17 2012-03-22 Robertson John S Systèmes de stockage et de conversion d'énergie
WO2021089276A1 (fr) * 2019-11-08 2021-05-14 Casale Sa Contrôle d'une boucle de synthèse d'ammoniac à charge partielle
AU2021276065A1 (en) * 2020-05-18 2023-02-02 Topsoe A/S Method for the control of pressure in a loop for the preparation of ammonia or methanol
WO2023099743A1 (fr) * 2021-12-03 2023-06-08 Thyssenkrupp Industrial Solutions Ag Procédé permettant de faire fonctionner un système à ammoniac et installation de fabrication d'ammoniac
WO2023217850A1 (fr) * 2022-05-12 2023-11-16 Casale Sa Méthode de contrôle d'un convertisseur d'ammoniac ou de méthanol
EP4332694A1 (fr) * 2022-08-12 2024-03-06 Air Products and Chemicals, Inc. Procédé et système de commande de production et de stockage de gaz industriels

Also Published As

Publication number Publication date
EP4620913A1 (fr) 2025-09-24

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